Liquid level regulating apparatus



S. G. GLICK LIQUID LEVEL REIGULATING APPARATUS Filed June 17, 1947 Feb. 3, 1953 Inventor His Attbrney k, m e m w. y s

Patented Feb. 3, 1953 UNITED STATES PATENT OFFICE LIQUID LEVEL REGULATING APPARATUS Sylvan G. Glick, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application June 17, 1947, Serial No. 755,207

Claims.

My invention relates to liquid level regulating apparatus, more particularly to liquid level regulating apparatus for a tower through which a gas-absorbing liquid flows downward in contact with the ga flowing upward, the liquid collecting in the bottom of the tower, and has for its object simple and reliable apparatus for maintaining a predetermined liquid level in thebottom of the tower or in any other container to which liquid is supplied.

My invention is especially useful in connection with the apparatus for separating gases disclosed in U. S. Patent Reissue 18,958, issued to Robert R. Bottoms on September-'26, 1933.

In carrying out my invention in one form, I utilize a horizontal centrifugal liquid pump which is driven continuously and which has its inlet opening positioned at substantially the same level as the liquid level to be maintained and connected to the container by a pipe. A gas outlet pipe for the pump, may be provided if necessary or desirable, as may also a check valve in the outlet pipe of the pump for preventing the return flow of liquid through the pump when the pump loses prime.

For a more complete understanding .of my invention reference should be had to the accompanying drawing, the single figure of which shows in diagrammatic form gas separation apparatus embodying my invention.

Referring to the drawing, I have shown my invention in one form as applied to the maintenance of a predetermined level of gas laden liquid I, which collects in the bottom .of the gas separation tower 2. I provide a liquid pump 3 of a centrifugal type having a horizontally disposed rotor 5 with radial vanes 5 mounted to operate in an enclosing casing 6 provided with a central inlet opening I and a peripheral outlet opening 8. This pump is mounted at such a level that its inlet opening I is at substantially the same height as the level of the liquid l to be maintained. The inlet opening I is connected directly to the bottom of the tower 2 by means of a pipe 9 which I have found should preferably be horizontal as shown for the most satisfactory operation. The rotor t of the pump is driven continuously at a substantially constant speed by means of an electric motor l0.

During its operation the pump withdraws liquid from the bottom of the tower 2 until the level of the liquid l is somewhat below the upper inner surface of the connecting pipe 9 so that enough gas flows from the tower through the empty part of the pipe above the liquid in the pipe to the pump to prevent the generation of liquid pressure in the pump. Thereupon th liquid pumping operation stops and by means of a check valve H in the outlet pipe l2 of the pump the return or reverse flow of fluid through the pump is prevented. It will be understoodthat the speed of the rotor of the pump and the rotor clearances are such that no appreciable gas pressure is generated in the pump when the pump isnot pumping liquid.

The level of the liquid I may drop to a point uncovering a substantial portion of the left-hand end of the pipe 9. In a typical installation the liquid level when the pump stopped liquid pumping operation, i. e. lost its prime, was at a point above the inside lower wall of the pipe substan tially three-fourths of the inside diameter of the pipe 9. Therefore, the gas space in the upper portion of the pipe 9 represented by the upper one-fourth of its inside diameter was sufficient to supply enough gas to the pump to keep it from pumping liquid. This liquid level when liquid pumping is stopped momentarily is the predetermined liquid level maintained by the pump.

As the level of the liquid thereafter rises from the addition to the liquid supply, the gas space in the pipe 9 is decreased until finally the pipe 9 is completely closed again by the liquid, or nearly closed to a point where the pump is suificiently flooded to prime it and pumping of liquid is resumed. For the purpose of assisting the priming of the pump, a gas vent pipe [3 of small size as compared with the pump inlet pipe 9 is connected to the pump at its highest point where the gas collects and extends upward far enough to maintain a desired liquid level head for the'pump when the pump is operating. With small pumps suificient gas may be exhausted through the pipe 9 back into the tower to provide for priming of the pump.

In a typical installation the pumping and nonpumping periods were repeated in rapid succession and were of substantially equal duration, each period being substantially one second.

In the operation of the complete gas separation apparatus to which my invention is applied a suitable liquid, preferably a mixture of monoethanolamine and water, is fed into the top of the tower 2 through a pipe I4 and flows downward slowly through the tower over a suitable filler material effecting efiicient contact with a C02 laden gas supplied to the bottom of the tower through a pipe l5. The filler material in the tower preferably consists of short cylindrical tubes [6 of porcelain, known as Raschig rings. In its passage upward through the tower the gas loses its CO2 which is absorbed by the liquid and the purified gas passes out at the top of the tower flirough a pipe ll, a gas cooler l8, a liquid separator I9, and thence through a pipe 20 to the apparatus using it, such as an electric furnace. As shown, the upper end of the vent pipe I9 of the pump is connected to the pipe H. The liquid is returned by a pipe I9 from theseparator to the bottom of the tower 2.

The liquid I containing the absorbed CO2 gas is forced by the pump 3 through the pipe l2, the heat exchanger 2| in which it is heated, and a pipe 22 to the upper end of a second tower 23 and passes downward slowly over Raschig rings in the tower. As it descends, the liquid is heated by a vapor arising from a boiler 24 at the bottom of the tower and CO2 is released from the liquid. The boiler 24 is heated by suitable means, not shown, and is maintained at a temperature at which most of the remaining CO2 is released from the solution. The released CO2 gas passes out at the top of the tower through a pipe 25 and then through a gas cooler 26 and a liquid separator 21 from which any liquid remaining in the gas is returned by the pipe 28 to the boiler. An outlet pipe 29 is provided for the CO2 gas.

By means of a centrifugal pump 30 the hot liquid, substantially free of CO2, is drawn off from the boiler 24 and passed through the heat exchanger 21 where it gives offsome of its heat to the liquid supplied by the pipe I2. From the heat exchanger 2| the COz-iree liquid passes through a cooler 3| and then through the pipe [4 to the upper end of the tower 2 to repeat the cycle.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. The combination with a container to which a liquid is supplied, of means for maintaining a predetermined liquid level in said container comprising a horizontally disposed centrifugal liquid pump having inlet and outlet openings, a substantially horizontal pipe connecting said inlet opening to said container in such position that the upper wall of said pipe is above said liquid level and the lower wall of said pipe is below said liquid level, and a motor for driving said pump continuously thereby to pump liquid from said container until the level of the liquid is lowered to said predetermined level partly uncovering the end or" said pipe to admit gas to said pump and stop the pumping of liquid until the level of the liquid rises sufliciently to prime the pump whereupon the pumping of liquid is resumed.

2. The combination with a container to which a liquid i'ssupplied, of means for maintaining a predetermined liquid level in said container comprising a horizontally disposed centrifugal liquid pump having inlet and outlet openings, a substantially horizontal pipe connecting said inlet opening to said container in such position that the upper wall of said pipe is above said liquid level and the lower wall of said pipe is below said liquid level, a motor for driving said pump continuously thereby to pump liquid from said container until the level of the liquid in said container is lowered to said predetermined level at which level the end of said pipe is partly unoov-- ered to allow gas to pass into the pump and stop the pumping of liquid until the level of the liquid rises sumciently to prime the pump whereupon the pumping of liquid is resumed, and a check valve in an outlet pipe for said pump for preventing the reverse flow of liquid through said pump. 3. The combination with a container to which a liquid is continuously supplied, or means for maintaining a predetermined liquid level in said container comprising a horizontally disposed centrifugal liquid pump having inlet and outlet openings, a substantially horizontal pipe connecting said inlet opening to said container in such position that the upper wall of said pipe is above said liquid level and the lower wall of said pipe is below said liquid level, a motor for driving said pump continuously thereby to pump liquid from said container until the level of the liquid is lowered to said predetermined level to be maintained at which level the end of said pipe is partly uncovered to allow gas to pass into the pump and stop the pumping of liquid, a check valve in an outlet pipe for said pump for preventing the reverse flow of liquid through said pump, and a gas vent pipe for said pump connected to substantially the highest point of said pump and extending upward to maintain a liquid head when said pump is pumping liquid,

4. The combination with a container to which a liquid is supplied, of means for maintaining a predetermined liquid level in said container comprising a horizontally disposed centrifugal liquid pump provided with a casing and a rotor in said casing having suficiently great clearances as to prevent the generation of appreciable gas pressure in said pump, a substantially horizontal inlet pipe connecting the center of said casing with said container in such position that the upper wall of said pipe is above said liquid level and the lower wall of said pipe is below said liquid level, a substantially horizontal outlet pipe connected to the periphery of said casing, a motor for driving said rotor continuously thereby to pump liquid from said container through said inlet pipe until the level of the liquid is lowered to partly uncover the end of said inlet pipe connected to said container whereupon gas passes into said casing and stops the pumping of liquid from said container, 3, check valve in said outlet pipe for preventing the reverse flow of liquid through said pump, and a gas vent pipe connected to the top of said casing extending upward externally of said pump to maintain a liquid head when said pump is pumping liquid.

5. An apparatus for maintaining a predetermined liquid level in a container to which a liquid is supplied, comprising a horizontally disposed centrifugal liquid pump provided with a casing and a rotor in said casing having sufficiently great clearances to prevent the generation of appreciable gas pressure in said pump, a substantially horizontal inlet pipe connecting the central portion of said casing with said container in such position that the upper wall of said pipe is above said liquid level and the lower wall of said pipe is below said liquid level, an outlet pipe connected near the periphery of said casing, a motor for driving said rotor continuously thereby to pump liquid from said container through said inlet pipe until the level of the liquid is lowered to partly uncover the end of said inlet pipe which is connected to said container whereupon gas passes into said casing and stops the pumping of liquid from said container, and a check valve in said outlet pipe for preventing the reverse flow of liquid through said pump.

SYLVAN Gr. GLICK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

